IMMUNOBIOLOGY OF SCRAPIE VIRUS INFECTION

瘙痒病是一种自然发生的海绵状脑病。 引起临床和病理变化的绵羊和山羊 类似于人类的克雅氏病和库鲁病。一个 一种称为PrP的独特蛋白质被发现是一种 羊瘙痒病感染性和IS纯化样品的主要成分 一些人认为它才是真正的感染源。我们 先前分离到的两个PrP mRNA的cDNA克隆 被瘙痒病感染的小鼠的大脑。我们已经给克隆的小鼠结扎了。 PRP基因插入牛乳头状瘤表达载体的研究 病毒(BPV)和诱导小鼠上皮细胞PrP合成 细胞。为了测试这些表达的蛋白质可能的传染性， 将超声处理的细胞悬液经大脑内接种到 断奶的RML小鼠。到接种后160天，没有小鼠感染 出现瘙痒的临床迹象表明PrP可能不是 传染性瘙痒病病原体，但更有可能是正常的 细胞蛋白质以聚集形式积累的细胞蛋白质 疾病过程的结果。有可能-- 内源性基因产物结果的翻译修饰 在制造传染性瘙痒病时还没有被 完全排除在外。 因为动物组织没有提供令人满意的底物 对于瘙痒病病原体的生化分析或分离，我们 已经继续致力于发展瘙痒病感染组织 文化体系。为了实现这一目标，神经母细胞瘤细胞系 小鼠来源成功地感染了瘙痒病原体。 被感染的培养物保存了21代，很好 超出了确保复制具有 发生了。在这种病原体中，感染似乎是特定物种的。 从仓鼠脑中提取的没有感染小鼠的来源 神经母细胞瘤细胞系。现已派生出阳性克隆 从这些原始文化中。它们大约含有50-100个 折叠比在原始培养中发现的更多的试剂，应该 提供一种新的、更均一的瘙痒病制剂来源。

Scrapie is a naturally occurring spongiform encephalopathy of sheep and goats which causes clinical and pathological changes similar to those of Creutzfeld-Jakob and Kuru diseases of man. A unique protein called prion protein (PrP) has been found to be a major component of purified samples of scrapie infectivity and is believed by some people to be the actual infectious agent. We previously isolated two cDNA clones of the PrP mRNA from scrapie-infected mouse brain. We have ligated the cloned mouse PrP cDNA into an expression plasmid containing bovine papilloma virus (BPV) and have induced PrP synthesis in mouse epithelial cells. To test the possible infectivity of these expressed proteins, sonicated cell suspensions were inoculated intracerebrally into weanling RML mice. By 160 days post-inoculation no mice had developed clinical signs of scrapie suggesting that PrP may not be the infectious scrapie agent, but is more likely to be a normal cellular protein which accumulates in aggregated forms as a result of the disease process. The possibility that post- translational modification of the endogenous gene product results in creation of the infectious scrapie agent has not been completely excluded. Because animal tissues have not provided satisfactory substrates for the biochemical analysis or isolation of the scrapie agent, we have continued to work on development of scrapie infected tissue culture systems. Toward this goal neuroblastoma cell lines of mouse origin were successfully infected with scrapie agent. Infected cultures were maintained through 21 passages, well beyond the number needed to assure that replication had occurred. Infection appeared to be species-specific in that agent derived from hamster brain did not infect the mouse derived neuroblastoma cell lines. Positive clones have now been derived from these original cultures. They contain approximately 50-100 fold more agent than was found in the original cultures and should provide a new, more homogenous source of scrapie agent.